You can send me your feedback or suggestion here. If there is something missing in the theme then you can ask me to add.
Also, if you are willing to add it yourself then feel free to open a pull request after making changes.
This form is setup using SimpleForm. You can get your own API token and update it in the _config.yml file.
But remember, php forms will not work on Jekyll.
More about jekyll forms here: https://blog.webjeda.com/jekyll-subscribe-form/
The styles for the form is included in this page. I haven’t included it in the main css because the form has at least 25 lines of css and it is used only on this page. So including it in main css file doesn’t make sense.